Yup, what Jimbo wrote
I had come to the same conclusion. Whenever I heard stories of a Tai Chi guy who could fight, he also had HARD style training when he was younger. I.e. usually not just Tai Chi alone. It was sometimes met with opposition...dang Tai chi almightyists!!!
I have written on other forums in the past and others have said before me that:
Tai Chi makes whatever or other art you do = Better.